2 layers61.8 × 21.6 mm
USBQuadMouse
PR77/CH554_USBQuadMouseKeyboard
CH554 based USB to Quadrature Mouse and Keyboard Interface
24 parts8MIT
2 layers107.7 × 49.8 mm
USBAuxKeyboard
PR77/CH554_USBAuxKeyboardCH554 base AUX Keyboard Interface (Macro Pad OR3)
- Size
- 107.7 × 49.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 66
- Nets
- 44
- Pads
- 256
- Tracks, vias
- 481, 191
- Pours
- 9
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 1 Mar 2026
- Updated
- 28 Sep 2026
Overview
USBAuxKeyboard is an open-source printed circuit board by PR77, from the PR77/CH554_USBAuxKeyboard repository on GitHub, published under the MIT licence. It is a 2-layer board of 107.7 × 49.8 mm with 66 parts on 44 nets, routed with 481 tracks and 191 vias.
It is built around the CH554T, WS2812B and SP0503BAHTG, with the SP0502BAHTG, IRLML6402 and SS16 among its other parts. Its parts include 18 diodes, 17 capacitors, 12 resistors, 4 switches and 3 connectors. It belongs with the keyboards and input boards and the 8051 (CH55x, STC, AT89) boards of this library.
Main components
6
CH554T
TSSOP-20TSSOP-20 Microcontrollers (MCU/MPU/SOC) ROHSWCH (Nanjing Qinheng Microelectronics)Microcontrollers (MCU/MPU/SOC)
WS2812B
5mm X 5mm Surface Mount RGB LED with Intelligent ControlWorldsemiUncategorised
SP0503BAHTG
SOT-143-55℃~+125℃ 10A@8/20us 14V 150W@8/20us 30pF、60pF 5.5V 6V 80nA ESD IEC 61000-4-2、IEC 61000-4-5、IEC 61000-4-4 Three channels Unidirectional SOT-143 ESD and Surge Protection (TVS/ESD) ROHSTECH PUBLICESD And Surge Protection (TVS/ESD)
SP0502BAHTG
SOT-23-40℃~+125℃ 100nA 2 30pF 5.5V 8.5V IEC 61000-4-2 TVS Unidirectional SOT-23 ESD and Surge Protection (TVS/ESD) ROHSLittelfuseESD And Surge Protection (TVS/ESD)IRLML6402
SOT-23-55℃~+150℃ 1 P-Channel 1.3W 110pF 12nC 145pF 20V 3.7A 400mV 633pF 65mΩ@4.5V P-Channel SOT-23 MOSFETs ROHSGuangdong HottechMOSFETs
SS16
SMA(DO-214AC)-55℃~+150℃ 100uA@60V 1A 60V 700mV@1A Independent SMA(DO-214AC) Schottky Diodes ROHSFUXINSEMISchottky Diodes
README
README.mdCH554 AUX KEYBOARD INTERFACE
USB MACRO PAD (AUX Keyboard Interface) based on the WCH554 MCS51 based chip with USB Device + Host Interface.
Warning
This design has not been compliance tested and will not be. It may cause personal damage to you or others. I take no responsibility for this. I accept no responsibility for any damage to any equipment that results from the use of this design and its components. IT IS ENTIRELY AT YOUR OWN RISK!
Overview
This project is essentially an open source macro pad which emulates a USB Keyboard, Mouse and Comsumer Device. Additionally, there is an OUT USB end point supported to allow for HOST communication back to the device. My target is to make this easily configurable so different functions can be added to the Rotary Encoder, Push Buttons and OLED display. I'm using this project as an opportunity to learn more about the WCH55x micro controller.
Appearance Final PCB Version
PCB version has been routed manufactured and tested. Gerbers and design now available as it works as expected. Here is the usual 3D artwork of the design.
Credits
I refacted a lot of the original libraries into various software components. However there were some repos which provided me with excellent information, tools and resources;
Parts
66| Qty | Value | Footprint | References |
|---|---|---|---|
| 17 | 100N | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C2, C3, C4, C5, C6, C7, C8, C10, C11, C12, C13, C14, C15, C16, C17 +1 |
| 12 | WS2812B | LED_SMD:LED_WS2812B_PLCC4_5.0x5.0mm_P3.2mm | D5, D6, D7, D8, D9, D10, D11, D12, D13, D14, D15, D16 |
| 5 | MountingHole_Pad | MountingHole:MountingHole_2.2mm_M2_Pad_Via | H1, H2, H3, H4, H5 |
| 3 | 10K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R6, R11, R12 |
| 3 | SP0503BAHT | Package_TO_SOT_SMD:SOT-143 | D2, D17, D18 |
| 2 | 0R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R5, R7 |
| 2 | 10R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R3, R4 |
| 2 | 22R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R8, R9 |
| 2 | 5K1 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R2 |
| 2 | SP0502BAHT | Package_TO_SOT_SMD:SOT-23 | D3, D4 |
| 1 | 100K | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R10 |
| 1 | 5V | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP2 |
| 1 | Buzzer | Buzzer_Beeper:Buzzer_15x7.5RM7.6 | BZ1 |
| 1 | CH554T | Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm | U1 |
| 1 | IRLML6402 | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | OLED | Connector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical | J3 |
| 1 | RotaryEncoder_Switch | Rotary_Encoder:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mm | SW3 |
| 1 | SS16 | Diode_SMD:D_SMA | D1 |
| 1 | SW_BOOT | Button_Switch_SMD:SW_SPST_B3U-1000P | BOOT |
| 1 | SW_MACRO_1 | Button_Switch_Keyboard:SW_Cherry_MX_1.00u_PCB | SW2 |
| 1 | SW_MACRO_2 | Button_Switch_Keyboard:SW_Cherry_MX_1.00u_PCB | SW4 |
| 1 | SW_MACRO_3 | Button_Switch_Keyboard:SW_Cherry_MX_1.00u_PCB | SW5 |
| 1 | SW_RESET | Button_Switch_SMD:SW_SPST_B3U-1000P | RESET |
| 1 | Serial | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J1 |
| 1 | USB_C_Receptacle_USB2.0 | Connector_USB:USB_C_Receptacle_HCTL_HC-TYPE-C-16P-01A | J2 |
| 1 | VBUS | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1 |
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Questions
How big is the USBAuxKeyboard PCB?
It measures 107.7 × 49.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the USBAuxKeyboard use?
66 parts, built around the CH554T, WS2812B, SP0503BAHTG and SP0502BAHTG. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the USBAuxKeyboard KiCad files?
From the PR77/CH554_USBAuxKeyboard repository on GitHub, at the commit this page was made from: the board is Hardware/USBAuxKeyboard.kicad_pcb and its schematic Hardware/USBAuxKeyboard.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the USBAuxKeyboard design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).